Some display devices, such as liquid crystal displays (LCDs), often use a backlight as a light source to display an image. Typically, the backlight is on at a constant, preselected brightness level to illuminate the display panel. The brightness level of the backlight can be high or low. While a brighter backlight usually results in a higher image quality, it results in high power consumption. High power consumption is disadvantageous, especially for a portable display system that draws its power from a battery. Adjusting the backlight level to a lower brightness decreases power consumption but yields lower image quality, for example with noticeable visual artifacts in parts of the image that show bright, saturated colors.
Different techniques have been developed to optimize the backlight level by balancing the image quality concerns with the power conservation goals. One such technique involves dynamically adjusting the global backlight level as an image is displayed. However, the dynamic global backlight adjustment technique has room for improvement. For example, dynamic adjustment often results in a backlight level that is higher than what is needed to show a high-quality image, using more power than necessary.
A method of adjusting the backlight level in a power-efficient manner without compromising image quality is desired.